Enhanced spectrofluorimetric determination of aflatoxin M1 in liquid milk after magnetic solid phase extraction

A simple and sensitive method using magnetic solid phase extraction (MSPE) followed by spectrofluorimetric detection has been developed for separation and determination of aflatoxin M-1 (AFM(1)) in liquid milk. The method is based on the extraction of AFM(1) on the modified magnetic nanoparticles (MMNPs) and subsequent derivatization of extracted AFM(1) to AFM(1) hemi-acetal derivative (AFM(2a)) by reaction with trifluoroacetic acid (TFA) for spectrofluorimetric detection. Magnetic nanoparticles (MNPs) coated by 3-(trimethoxysilyl)-1-propantiol (TMSPT) and modified with 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) were used as adsorbent in MSPE procedure. Influential parameters affecting the extraction efficiency were investigated and optimized. Under the optimum conditions the calibration curve for AFM(1) determination showed good linearity in the range 0.030-10.0 mu g L-1 (R-2 = 0.9991). The repeatability and reproducibility (RSD%) for 0.050 mu g L-1 of AFM(1) were 4.5% and 5.3%, respectively and limit of detection limit (S/N = 3) was estimated to be 0.010 mu g L-1. The developed method was successfully applied for extraction of AFM(1) from spiked liquid milk and natural contaminated liquid milk. The good spiked recoveries ranging from 91.6% to 96.1% were obtained. The results demonstrated that the developed method is simple, inexpensive, accurate and remarkably free from interference effects. (C) 2014 Elsevier B.V. All rights reserved.